Why is acrylic the preferred material for number plates?

All vehicles using the United Kingdom’s road network are required by law to display their registration marks in the form of number plates. One of the many regulations pertaining to the display of number plates revolves around the retroreflecting property of the material used to manufacture number plates. As stipulated in the Road Vehicles (Display of Registration Marks) Regulations 2001 ( (Schedule 2, Regulation 10, Part 1), retroreflecting number plates must conform to specifications of the British Standard BS AU 145d certification (or equivalent) for all vehicles registered after 1 September 2001.

The reflective property of acrylic number plates, in combination with the background and lettering colours, ensures a higher level of visibility on the road, both during the day and night.

With this requirement in mind, acrylic has become the preferred material used in the manufacturing of number plates. But what is acrylic exactly, and what is its appeal?

What is acrylic?

Acrylic, or acrylic plastic polymers, is a synthetic plastic compound which consists primarily of the derivatives of acrylic acid. The monomer, or base molecule, of acrylic acid is methyl methacrylate (CH 2 =C(CH 3)). Polymers are formed when acrylic acid is exposed to a catalyst (such as organic hydroperoxides). The polymers are usually manufactured in rods, tubes, flat sheets and powder for supply to second tier manufacturers.

Acrylic Manufacturing

Acrylic plastic polymers can be synthesized into a wide variety of acrylic products used in a diverse range of industries. The polymers can also be blended with other emulsions and solids to produce products such as, among others, acrylic paints, polyacrylamide (clarifying agent in water treatment), and superabsorbent polymer (SAP, frequently used in disposable baby diapers).

However, the most popular form of acrylic is polymethyl methacrylate (PMMA). PMMA is a highly durable compound that is able to withstand the sun’s ultraviolet radiation and extreme weather fluctuations for long periods of time. They are relatively strong, yet are quite flexible, and can be moulded, cut and trimmed, drilled, and even tinted without losing their structural integrity.

In addition, PMMA is highly valued owing to its clarity. Depending on the chemical additives used, PMMA can be customised to meet specific levels of light transmissions, flow rates, heat resistance and impact strength (ten times stronger than conventional materials at half the weight). This is why acrylics are used in wildly different environments, ranging from laptop glass and fabric to skylights and viewing ports of submarines.

Acrylic Number Plates

In UK, acrylic is used by almost all of private plates manufacturers. The acrylics are usually supplied to them in 3.2 thick, pre-laminated flat sheets that have already been coloured back or yellow. This allows manufacturers to simply cut them into the desired rectangular sizes.